How big should an intake be?
- Thread starter AJ12Gamer
- Start date
Michael Hunt
Well-Known Member
I would just go with whatever size the inlet/outlet of the fan is. Reducers tend to restrict airflow and you would not be moving 400cfm. I use one 450cfm vortex as my exhaust and it has enough suction to draw all of the hot air out, and bring cool air in for my light and cab. i even use a fan controler since having it on high just makes things too cold. Hope this helps
- Thread starter
- #4
Because, if you have a 6" active out you would need a 12" passive in. If you do like for like you would need two fans. 6" in and 6" out. Air needs to replenish itself every 3 mins. Hope this helps.
not quite, for 6" exhaust (Pi x r x r, 3.14 x 9 = 28 sq. in) you would need around 56 sq in. intake. it could be 7 x 8 square cut out.
Lil Neutrino
New Member
For negative pressure to occur you need to be blowing air out at a higher velocity than you are taking it in. If you have air coming in faster than it goes out then it will create more pressure inside the enclosure and force air out where ever it can escape including cracks and whatnot. If the air is leaving the chamber faster than it is coming in it begins to create a vacuum which causes the negative pressure. Someone correct me if that's wrong in any way...not my specialty but that's how I understand it.
Having more intake area than exhaust will help reduce extraneous noise caused by the air "whooshing" in to the cabinet...the exhaust fans already guarantee that there will be some "whooshing" coming out.
Having more intake area than exhaust will help reduce extraneous noise caused by the air "whooshing" in to the cabinet...the exhaust fans already guarantee that there will be some "whooshing" coming out.
MisterPeabody
New Member
My rule of thumb is 3-4 times the area of intake as apposed to the exhaust. This will also keep things as quiet as possible. My cab is utilizing 365 cfm of active air drawn through two 4" holes. The passive air intakes are as follows. I have a 14x28 in the flowering area and a 12x12 located in the veg/clone area. This does OK, but even with this and 400 watt HPS below and T5's above, it's borderline cooling, and that's taking into account I have to use a chiller to maintain temps in the reservoirs...BUT airflow is no longer a problem. Peace
